Structure and Function of the Bacterial Heterodimeric ABC Transporter CydDC
| Autor: | Robert K. Poole, Stephen A. Baldwin, Mark Shepherd, Wesley I. Booth, Yvonne Nyathi, Masao Yamashita, Vincent L. G. Postis, Svetomir B. Tzokov, Per A. Bullough, Hao Xie |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Protein Structure
Cytochrome ATPase Bacterial Metabolism Biological Transport Active ATP-binding cassette transporter Heme Transporter Microbiology Biochemistry Structure-Activity Relationship chemistry.chemical_compound Structural Biology Membrane Biology Escherichia coli Protein Structure Quaternary Membrane Protein Molecular Biology Membrane Transporter Reconstitution Adenosine Triphosphatases biology Escherichia coli Proteins Cell Biology Periplasmic space Transmembrane protein ABC Transporter chemistry biology.protein ATP-Binding Cassette Transporters Protein Multimerization Cysteine Hemin |
| Zdroj: | The Journal of Biological Chemistry |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m114.590414 |
| Popis: | Background: The ABC transporter CydDC, which pumps sulfur compounds, is required for assembly of the bacterial respiratory machinery. Results: ATP hydrolysis by CydCD in response to sulfur compounds is modulated by hemes. Conclusion: Hemes regulate CydDC in pumping sulfur compounds. Significance: This work is a first step in understanding the structure, function, and regulation of a protein vital to the assembly of the respiratory machinery. In Escherichia coli, the biogenesis of both cytochrome bd-type quinol oxidases and periplasmic cytochromes requires the ATP-binding cassette-type cysteine/GSH transporter, CydDC. Recombinant CydDC was purified as a heterodimer and found to be an active ATPase both in soluble form with detergent and when reconstituted into a lipid environment. Two-dimensional crystals of CydDC were analyzed by electron cryomicroscopy, and the protein was shown to be made up of two non-identical domains corresponding to the putative CydD and CydC subunits, with dimensions characteristic of other ATP-binding cassette transporters. CydDC binds heme b. Detergent-solubilized CydDC appears to adopt at least two structural states, each associated with a characteristic level of bound heme. The purified protein in detergent showed a weak basal ATPase activity (approximately 100 nmol Pi/min/mg) that was stimulated ∼3-fold by various thiol compounds, suggesting that CydDC could act as a thiol transporter. The presence of heme (either intrinsic or added in the form of hemin) led to a further enhancement of thiol-stimulated ATPase activity, although a large excess of heme inhibited activity. Similar responses of the ATPase activity were observed with CydDC reconstituted into E. coli lipids. These results suggest that heme may have a regulatory role in CydDC-mediated transmembrane thiol transport. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|